如何通过oracle选择语句，将以下有规则的记录以树型结构的方式输出呢

先转换成数字
SQL> select to_number(replace(substr(col1, 1, 3)||'.'||substr(col1, 4), '0', '')) from test_1;TO_NUMBER(REPLACE(SUBSTR(COL1,1,3)||'.'||SUBSTR(COL1,4),'0',''))
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                                                               1
                                                             1.1
                                                            1.11
                                                            1.12
                                                            1.13
                                                             1.2
                                                            1.21
                                                            1.22
                                                            1.23
                                                            1.24
                                                             1.3
                                                            1.31
                                                            1.32
                                                            1.33
                                                            1.34
                                                           1.341
                                                           1.34217 rows selected.SQL> select * from test_1
  2  order by to_number(replace(substr(col1, 1, 3)||'.'||substr(col1, 4), '0', ''));COL1                           COL2
------------------------------ --------------------------------------------------
001                            高中
001001                         高一
001001001                      高一1班
001001002                      高一2班
001001003                      高一3班
001002                         高二
001002001                      高二1班
001002002                      高二2班
001002003                      高二3班
001002004                      高二4班
001003                         高三
001003001                      高三1班
001003002                      高三2班
001003003                      高三3班
001003004                      高三4班
001003004001                   高三4班1小组
001003004002                   高三4班2小组